Effective management of energy consumption at the consumer level is a vital part of the future Smart Grids. An efficient Home Energy Management System (HEMS) is a crucial and necessary interface between the Demand Side Management (DSM) techniques and the actual control of the energy consumption by the users in a building. In this paper we present an implementation of an efficient and extremely cost-effective Zigbee based Home Area Network (HAN) that seamlessly integrates the HEMS with the DSM within the goals and constraints set by the user while keeping the consumers informed about their energy consumption through a user interface. This paper focuses on the hardware design of a smart socket in the HAN that includes a wireless communication interface, a smart energy meter and a switching mechanism to control the appliances. The emphasis is on keeping the cost of the design to a minimum to encourage the deployment of the proposed energy managing home area network in the developing countries where there is a dire need for energy management.
Pollution of the urban environment is fast becoming a grave threat to urban dwellers as levels of toxicity increase to beyond safe limits. This is especially true in many low-and middle-income nations where the rapid pace of industrialization and development, coupled with fast growing and extremely dense urban centres, are leading to more serious environmental hazards for citizens. These include urban air pollution, which is diffi cult to tackle, especially in cities or nations where resources are scarce, awareness is minimal and the urban environment is not an issue receiving government attention. This paper describes the development and pilot implementation of the Volunteer Internet-based Environment Watch (VIEW) in two cities in Pakistan. This system, which makes use of volunteers and their personal computers to monitor air pollution, can send valuable local environmental data to a central server for storage and collation. The system was successfully developed and deployed in a relatively small period of time, with a small budget and limited human resources. The paper describes the various decisions and choices made with regard to: accessing funding; the organization; the timeframes and work plan; the choices made with regard to physical deployment of the system; budgeting and other project issues. This pilot in Pakistan could serve as a model for similar efforts in other countries.
This paper provides a cost effective and generic solution for urban air pollution monitoring using existing computing resources and infrastructure. The design has been modularised into three subsystemsthe Data Acquisition System (DAS), Data Transmission System (DTS), and the Data Collation System (DCS). The DAS is composed of ground-based sensing equipment attached to the PCs, of citizen-volunteers geographically spread out in a city, connected to a central server via the internet. The devices periodically send snap-shots of urban environmental conditions of their respective localities to the central server using the DTS. Here, the DCS seamlessly aggregates received data to build a comprehensive database (DB) of the history of environmental conditions in a given urban setting and allows internet users to view analyses run on that data. I.
This paper proposes an analytical formulation-based minimization of DC link current ripples for interleaved parallel inverter systems. Parallel inverter systems find applications in multiple fields. The interleaved superposition of the DC link currents in these systems can potentially be adjusted to mitigate the overall harmonics consequently reducing the DC link capacitor size. To this end, a widely used approach in the literature is the Fourier analysis based on interleaving focusing on dominant harmonic mitigation. However, it leaves room for a generic analytical mechanism to provide time shifts leading to an optimal reduction in DC-link ripples. The goal of this work is to target this optimal reduction by utilizing an analytical mechanism. The paper presents an alternate way of DC-link formulation in terms of the piece-wise sinusoids of inverter output currents for space vector modulation-based systems. The formulation is then used to numerically optimize the interleaved shifts for minimum ripples. Moreover, in addition to the traditional concept of fixed time interleaving, a contemporary concept of sequence-based interleaving is utilized, which is anticipated to have more flexibility in the implementation and additional switching synchronism with PWM rectifiers for back–back converters. Therefore, the sequence interleaving has also been utilized in conjunction with the proposed ripple reduction methodology. Further, an underexplored area of using the combined impact of sequence and time interleaving has also been applied in this work. These interleaving methods are shown to provide significantly improved DC-link ripple mitigation, as compared to existing methods, using numerical assessment followed by simulations and experimental evaluation.
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